A rider tumbles at Aintree last year – two horses died as a result of falls in 2011's Grand National. Photograph: Tom Jenkins

Campaigners are calling for a betting boycott of next weekend's Grand National, as latest figures reveal the death toll on Britain's racecourses.

Animal Aid has launched a Sanctuary Not Cruelty campaign, appealing to people to send money they might have put on the race to a horse sanctuary instead.

At least 23 horses died as a result of injuries on racecourses in March alone, with five animals dying in the first two days of the Cheltenham festival.

The death last week of Fox Hunt, a winner at Royal Ascot, caused an outcry at the Dubai Gold Cup. The race was stopped after Fox Hunt broke a leg and collapsed during the running but was then re-scheduled for later in the day, when a further two horses were fatally injured.

There was huge controversy at last year's Grand National, when two horses died as a result of falls and Jason Maguire, the rider of the winning horse, Ballabriggs, received a five-day suspension for using his whip with excessive frequency.

Animal Aid spokesperson Fiona Pereira said: "We are asking the public to remember how they felt about the 2011 race and to donate their usual 'flutter' to our two specially selected sanctuaries, both of which require funding to rescue horses in need – including ex-racehorses.

"As well as individuals, we hope that company sweepstakes will support our initiative. Helping racehorses in their retirement is particularly important. It's one of horse racing's darkest secrets that many thoroughbreds face neglect or are slaughtered for meat when their racing careers are over or they are deemed financially unviable."

There have been changes to two fences at Aintree, near Liverpool, ahead of Saturday's race. From a field of 40 horses, only 19 finished the race in 2011. Twenty horses have died as a result of competing in the Grand National since 2000.

Television and radio commentators were criticised at the time for ignoring the falls as the race continued, with one BBC commentator only referring to the fatalities by calling the body of a dead horse "an obstacle".

This year television companies have also been targeted in the Animal Aid campaign, which calls on commentators to properly report on, and investigate, any deaths during this year's Grand National.

"They seem to think they have to be sensitive for the viewer, but people do need to know what's going on on that course," said Dene Stansall, the grandson of an Aintree bookie who now keeps the country's only record of racehorse deaths for Animal Aid.

"Racing is not unlike being in the army for horses," said Stansall. "They're fed, kept fit and looked after, some even love it, but there is an ever-present risk.

"That is a risk of dying. Unfortunately horses aren't given a choice."

Dr Mark Kennedy, senior lecturer in animal welfare at Anglia Ruskin University, says risk in horse racing has to be tackled by the industry. He said the five deaths at Cheltenham were a reminder of the high risk horses are exposed to in steeplechasing and hurdling.

"In large meetings with more than 500 starts, such as the Cheltenham and Grand National meetings, we can expect two to three horses to die over the course of the meetings. These are not freak accidents; they are the predictable outcome of running horses at this level of risk.

"I sincerely believe the vast majority of those involved in racing genuinely and deeply care about their horses and hate to see them injured or killed," he said. "I do not suggest that I, or anyone else, have any right to demand a ban on jump racing. But I do believe we should clearly assess, acknowledge and discuss the risk horses are exposed to. If the risk is unacceptably high, we have to consider whether it is right to expose horses to risk of this magnitude."

Julian Thick, the managing director of Aintree, said: "Aintree is racing's shop window. It's a national treasure, a national institution and very much in our national psyche.

"We're very open about the risk, there is a risk in all sports and we never stand still on safety. This year we have put together a package of changes which will be very good for the race. This year is the 165th running. Last year we had a record 8.8 million people watching and 153,000 through the racecourse over the Grand National weekend.